Metal-organic halide perovskites are promising absorber materials for photovoltaics. However, these materials are delicate and degrade under harsh processing conditions (such as sputtering).
Tandem (multi-junction) photovoltaic devices require a transparent electrode at the top of the device through which light may reach the various layers in the device. This transparent electrode is often a transparent conducting oxide (TCO). The primary method for preparing most TCOs is sputtering.
Thus, tandem devices containing delicate materials in the top junction will require a less-aggressive method for preparing the TCO than sputtering to avoid damage to the material.